Carbon Dioxide Balance on Earth & Mars “Why do I care?” •Atmospheric CO2 helps regulate temps. On a planet. Temperatures determine if you can have liquid water! •CO2 is a green house gas. It allows visible light from the sun in, but traps heat (infrared energy). •CO2 also is used by plants on Earth to make food and support the entire planets food web! Earth’s CO2 Balance CO2 Reservoirs (sources/storage) • Atmosphere • Ocean (dissolved) • Rocks (CO2 combines with other minerals to form carbonate rocks) • Soil (carbonic acid) • Oraganics/ Living Organisms Earth’s CO2 Balance CO2 put into atmosphere by… 1. Volcanic eruptions 2. Respiring organisms (almost all organisms respire CO2 ). 3. Released by the ocean 4. Combustion of organic matter a. Burning fossil fuels (coal, oil, gas) b. Forest fires Earth’s CO2 Balance CO2 REMOVED FROM the atmosphere by… 1. Photosynthesis (Plants & photosynthetic plankton take in CO2 to make food. This circulates carbon in the world’s food web) 2. Absorbed by the ocean 3. Converted into rock Dissolved CO2 in ocean is incorporated into the shells of marine organisms. They die and accumulate on the ocean floor. This mixes with other sediment and gets compressed into rock. Earth’s CO2 Balance Importance of Plate Tectonics & Geologic Activity Because Earth is still hot in its interior it is still volcanically active & has plates that move & get melted in the mantle (supplying more magma). This renews CO2 in our atmosphere! MARS’S CO2 Balance Early Mars was warmer, with a thicker atmosphere, and had liquid water on the surface! What happened? Mars lost much of its initial CO 2 atmosphere when it became GEOLOGICALLY DEAD! Mars is smaller & lost internal heat faster No more volcanoes/plate tectonics. No way to replenish CO 2 in atmosphere! The CO 2 that is trapped in rocks can’t get recycled. Thinner CO 2 atmosphere = Cooler temps (it’s a GHG) Water & CO 2 freeze in ice caps! Less atmospheric pressure CO 2 in oceans escapes to air; Water evaporates MARS’S CO2 Balance Today CO 2 on Mars is : • Part of a thin atmosphere • Frozen in ice cap • Trapped in rock Remember: Mars has no organisms or oceans to cycle CO2 . Combustion cannot happen on Mars because there is not enough oxygen.
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